The invention relates more particularly to a device for packaging and dispensing a product comprising a container designed to contain the product that is to be dispensed, with the aid of a nozzle that has no air inlet and with which the container is fitted, the nozzle optionally being an integral part of said container or being mounted in a sealed manner on an open neck of said container.
There are in the prior art packaging devices of conventional structure that can be used to preserve and dispense a product in the form of doses or drops or in any other form, while maintaining its sterility for the entire duration of its use.
These devices are used particularly in pharmaceutical, cosmetic and food applications, and in some cases more particularly in opthalmological applications.
For example, the prior art includes such devices disclosed in patents FR 2 770 495, FR 2 638 428 and FR 2 661 401 in which a container is fitted with a dispensing nozzle that includes a bacteriological filter membrane which sterilizes the product when it is expelled from the container.
In these devices, the container comprises a flexible portion which, when squeezed by hand, forces the product through the bacteriological membrane, through the nozzle and out of said container.
It should be observed that, when a portion of product is expelled from the container, a partial vacuum is created inside the container and must be compensated for, either by admitting more air equivalent to the volume of product expelled, or by a corresponding reduction in the internal volume of the container, which can be done by causing a corresponding deformation of the container.
Present-day membranes do not allow product (liquid, semi-fluid or in suspension) to flow in one direction, i.e. from the interior of the container to the exterior, and air to flow in the opposite direction, i.e. from the exterior to the interior of the container, the reason being that the internal and external faces of the membrane are “wetted” by the passage of the product and the external face resists the entrance of new air.
In this type of device it is therefore necessary to provide a container whose internal volume is variable and reduces as the product contained inside it is dispensed.
This requirement results in unattractive-looking containers that are difficult to manipulate when not protected by a protective outer jacket, or difficult and expensive to manufacture if such a protective outer jacket is provided.
Another problem with these devices is that there is no way of dispensing highly viscous products as these require excessive pressure to force them through the sterilizing membranes, the pores of which are of extremely small diameter. Nor can they be used to dispense products in suspension where the particles axe stopped by the membrane.
Another kind of device that can be used to achieve a similar result is disclosed in FR 2 772 007. This comprises a rigid container designed to contain the product to be packaged, a hand pump of the type with no air inlet mounted on the container, said pump being intended to dispense the product in single doses, and a sterilizing filter placed in an air renewal passage formed in the base of the container.
The main problem with this kind of device is that the bottle is rigid and that a dispensing pump has to be used to dispense the product. Such a pump discloses in patent FR 2 772 007 contains numerous elements, including a dose-defining chamber and two valves for isolating said chamber and dispensing precise doses of product. This construction is very expensive and considerably increases the cost price of the device, and the cost of such a pump can be practically equivalent to that of the bottle itself. The cost of such a device makes it unsuitable for its use in certain applications such as, for example, opthamology, in which the products are sold cheaply and do not need precise dosing because the products are dispensed in drop form. A pump capable of dispensing drops requires very precise construction, which increases its cost by a corresponding amount.
Another problem with such a device is that the pump used has a push rod incorporating its own nozzle through which the product is dispensed. It is inherent in the construction of the pump that the push rod is movable and the product is dispensed when the push rod is released and returns to its initial position under the action of a return spring. This mobility of the push rod, and therefore of the nozzle through which the product is dispensed, makes this device unsuitable, and possibly even dangerous, for dispensing eye drops.
Another problem with a device comprising a pump is that it is impossible to sterilize it by heating it because the pump contains plastic components, some of which are inherently unable to tolerate the high temperatures indispensable for sterilizing the complete device before it is put to use.
Another difficulty with this kind of device is that the pump usually contains metal parts, such as the spring or the valves where these consist of steel balls, and these are incompatible with certain fragile or aggressive products or products that may produce an electrolytic effect.